hopkins



(No Model.) 2 Sheets-Sheet 1. E.-P. HOPKINS.

ELBGTRIO ARC LAMP.

NI). 573,464. Patented Dec. 22, 1896.

m: NORRIS Firms cc, PHOTLLUTHQ, WASHINGTON. n. c.

(No Model.) 2 Sheets-Sheet 2.

' E. P. HOPKINS.

ELECTRIC ARC LAMP.

' No. 573,464. Patented Dec. 22, 1896.

UNITED STATES PATENT OFFICE.

EDlVARD POWELL HOPKINS, OF NEV YORK, N. Y.

ELECTRIC-ARC LAMP.

SPECIFICATION forming part of Letters Patent N0. 573,464, dated December22, 1896.

Application filed June 13, 1894.

.To all whom it may concern.-

Be it known that I, EDWARD POWELL l-Ior- KINS, a British subject,residing in New York city, in the county and State of New York, haveinvented a certain new and useful Improvement in Electric-Arc Lamps, ofwhich the following is a specification.

The object I have in view is to produce a small, compact, and lightfocusing electricarc lamp, especially adapted for lantern projections,photography, and like purposes, which will give an absolutely steadylight, can be used in any position, and the light of which may beincreased or decreased at will without changing the regulation of thelamp itself, enabling the projection of dissolving effects with astereopticon and adapting the lamp for stage-lightin g and similarpurposes. The regulation of my lamp is dependent upon a peculiar actionof the electric arc hereinafter described, first observed by me or atleast first utilized by me for this purpose.

My invention consists in the several devices and combinations more fullyhereinafter ex plained, and pointed out by the claims.

In the accompanying drawings, forming a part hereof, Figure 1 is a sideview of the lamp with the side plates of its inclosing case removed.Fig. 2 is a similar view from the other side of the lamp, thelight-shield being in section. Fig. 3 is a side view of the lamp on asmaller scale with the side plate of the inclosing case in position.Fig. at is a top View of the lamp on the same scale as Fig. Fig. 5 is avertical section through the parts mounted on the main shaft of thedriving-clockwork with the other wheels of the train in elevation. Fig.6 is a vertical section on the line (3 6 in Fig. 5. Figs. 7 and 8 aresections showing the method of insulating the carbon-holders from theirsupports, and Fig. 9 is a diagram illustrating the circuit connectionsof the lamp.

The operative parts of the lamp are inclosed within or mounted upon aquadrangular box A of metal composed of a quadrangular frame and twoside plates secured thereto by screws. For projection purposes, forwhich the lamp is especially designed, the box Ais adj ustably mountedupon a U -shaped stand B. For this purpose to the rear of the box A issecured, by a substantial foot, a split clamping-sleeve a,

Serial No. 514,372. (No model.)-

having on opposite sides of the split lugs a, through which passes ascrew '1) for operating the clamp by means of a suitable thumbpiece. Theclamping-sleeve a slides upon a tube 0, which is mounted on a post 6],rising from the stand 13. The upper end of the tube 0 is screw-threadedand receives a screw 0', which bears against the upper end of the post(1. These parts give a vertical adjustment to the lamp, the clamp abeing for the purpose of giving a proximate and quick verticaladjustment by moving the clamp up and down on the rod d, while the screw0 enables an exact adjustment to be secured. The lamp, being carried bythe tube 0, turns freely upon the post d to obtain a lateral adjustment,which lateral adjustment is produced by a screw 6, passing through apost 6, rising from one side of the U-shaped stand and bearing againstone side plate of the box, while from the other side of the U-shapedstand rises a leaf-spring 6*, which presses inwardly against theface-plate on that side of the box. By turning the screw 6 forward thebox is pushed sidewise against the pressure of the spring, while byturning the screw backward the spring causes the box to follow thescrew.

The carbons in my lamp are fed together positively, Without regard tothe position of the lamp, by a spring-motor having a fixed position andoperated by a clock-spring having considerable initial tension. Theclockmovement is carried bytwo plates 0 O, Which are inclosed within thebox and supported from its top. The clock-movement comprises a mainshaft D, which projects beyond the plate G and has a squared end, onwhich is mounted a winding-wheel E,located outside of the box and havinga hub extending through the face-plate C of the box for engaging withthe main shaft. Upon this'main shaft is secured the inner end of thedriving-spring F, the outer end of this spring being attached to thestationary stud f. Upon the other end of the shaft D, on opposite sidesof the plate 0, are secured two pinions G G, engaging with racks H H forfeeding the carbons. The pinion G, which feeds the positive carbon, islarger than the pinion G, which feeds the negative carbon, thedifference in size being proportional to the difference in the burningrate of the positive and negative carbons, '6.

0., 1.66 to 1. This proportion is secured by making the pinion G onewith twenty teeth and the pinion (1 one with twelve teeth. The pinions GG being fixed to the shaft 1), the turning of that shaft by thewhirling-wheel E to wind up the spring will also turn the pinions G Gandwill move the racksll ll" in the direction of separating thecarbon-holders. The reverse movement of the shaft 1), under the effectof the springll, will move the racks 1f ll in the direction of feedingthe carbons together.

To retard the feeding movement, the shaft 1) is connected by wheels andpinions with an escapement g, which is operated as the shaft 1) isturned by the unwinding of the spring F, but is not operated by thereverse movement of the shaft. To accomplish this, there is mountedloosely on the shaft D a gear-wheel g, engaging with a pinion on theshaft which shaft is provided with a gearwheel engaging with a pinion onthe shaft 9 which latter shaft carries the scape-wheel. A ratchet-wheel71, fixed to the shaft l), is engaged by a spring-pawl 71/, carried bythe gear-wheel g. The pawl and ratchet permit the turning of the shaft1') to wind up the spring 1 and move the racks II If for separating thecarbon-holders without operating the eseapement. The rackba-r II issupported at its ends by guide-collars i 1?, sliding on a round red I,which extends from the bottom of the box through and above the top ofthe box. The collar 1: engages with the red I within the box and thecollar t" with the upper portion of the red I above the box. Thepositivecarbon holder l is connected by an L-shaped arm j with thecollar "1 the parts bcinginsulated,preferablywithmica,asillustrated inFig. 7. The rack-bar ll: is guided not only by the rod I, but also bythe opening through the top of the box A, with which it makes anaccurate iit. The rack 11, by means of which the negative carbon is fed,passes through and accurately fits a hole in the top of the box A. Atits upper end it is rigidly connected by a cross-piece 7; with avertical slide 7;, which is guided upon the face of a supportingplate K,mounted upon studs and thimbles secured to the front of the box A, butseparated therefrom by an airspace.

The slide in carries at its lower end the negative-carben holder l whichis mounted from the armature m of the series-wouud striking-magnet M andinsulated therefrom, as illustrated in Fig. 8. This magnet is preferablyone having a winding only upon one leg of the magnet, and having thearmature m pivoted upon the other leg of the magnet by means of a piecea of spring-brass, the play of the armature being regulated by a screwit, which passes through a slot in the armature and enters the otherpole-piece, the head of the screw limiting the'baclm'ard movement of thearmature.

To regulate and control the feeding move p,p1.'ojectiiig through therear of the box and having a milled head outside of the box for turningit. The forward movement: of the armature o is regulated by a screw o'passing through the armature and striking the pole of the magnet, whilethe retraction of the armature is limited by a stop p, secured by ascrew to the plate (1. The armature o carries a catch-arm which engages,when the armature is retracted, with the tail q of the escapement-vergeg, arresting the movement of the escapement and locking the train. "Whenthe armature o is attracted by the magnet N, the eseapement is releasedand the train of wheels is run by the spring F feeding the carbonstogether. Upon the plate K is mounted the light-shield t separatedtherefrom by an air-space and n-ovided with a forwardly-projectingtubular shield, which is slotted at the top and at the bottom to permitthe movement of the carbon and earbon holdcrs. "Within the shield andprojecting horizontally forward from i ts back plate belewthcecnter ofthe shield, and hence below the are, is an iron or steel plate 1, whichcut out so as to partially encircle the negative carbon, which plateperforms the double function of intercepting the passage of lightdownwardly through the slotted bottom of the shield and, by themagnetizing effect of the electric current, draws the are inwardly andprevents it from flaming up on the face of the positive carlmn. it alsoprevents the rising current. of air from blowing directly on the are.

Flexible cords (Q and it extend from the binding-posts and T through thetop and front of the box, and a re connected. with the positive andnegative carbon holders for conveying the electric current to them. andthrough the coils of the striking-magnet i l. The magnet N is located.in another circuit between the binding-posts S and T, which circuitincludes, preferably, an additional resistance U, which may, however, beomitted if the magnet N is made large enough and l v wound with asufficient length. of wire to give upon an L-shaped projection dependingthe amount of resistance required to prevent. an excessive flow ofcurrent through the magnet-coils and a consequent burning out of suchcoils.

In general the operation of my lamp is effected by the initialseparation of the carbons by the series nntgnet M (which separw tioncauses the formatitm or striking of the arc) and by the subsequentfeeding of the carbons together by the shunt-n1agnet Thenegative-carbon. holder projects somewhat beyond the positive-earbonholder, so that the axis of the negative carbon is some- IOU TIC

what in advance of that of the positive carbon. The effect of this is tocause the formation of the crater of the arc in an oblique position onthe forward side of the positive carbon and facing to the front, so thatthe light will be largely projected forward, and this effect is aided byarranging the carbons in an inclined position, as illustrated. Thenegative-carbon holder, being mounted upon a pivot, is moved by thestriking-magnet in an arc of a circle, and the point of the negativecarbon is therefore moved laterally and downwardly away from thepositive carbon, following the lateral course which the arc takes inpassing from one carbon to the other. The front of the lamp iseffectively protected from the heat of the arc, first, by thelight-shield O, and, second, by the front plate K. Since both of theracks enter the movement-box at the top and pass through openings whichthey fit closely, that box is made largely dust-proof, and is also mademore convenient for the mounting of the lamp.

Many advantages arise from the details of construction of my lamp, whichit is not necessary to call attention to in detail.

The principle of regulation of my electricarc lamp is based upon thefact observed by me from numerous experiments that the quantity ofcurrent or amperes flowing through the arc may be varied between quitewide limits without varying substantially the difference of potential atthe are itself-t. 6., that the difference of potential at the arc isindependent of the quantity of current, or substantially so. If the arcacted like an ordinary resistance, the voltage would have to beincreased in direct proportion to the amperes, according to Ohms law,and if a dif ference of potential of forty-five volts was required toproduce a flow of ten amperes, to increase the current to twenty ampereswould require ninety volts, assuming that the resistanee remained thesame. The apparent resistance, however, I have found does not remain thesame, but decreases with the increased current flow, and in some cases Ihave found that by increasing the current the difference of potential atthe carbons is actually lessened. The phenomenon is explained, I think,on the theory that with a small current a greater percentage of the heatproduced at the are is conducted away by the carbons themselves thanwith a larger current, thus permitting with the larger current theformation of a proportionately larger amount of the conducting carbonvapor which exists in the are.

In operating my lamp it is preferably connected with aconstant-potential circuit 1 2 through an adj nstable resistance IV, asillus trated in Fig. 9. Assuming the voltage of the circuit 1 2 to beone hundred and twenty volts and the magnet N to be adjusted to maintainapproximately forty-five volts at the are, I have found that byadjusting the resistance \V the current passing through the are can beincreased or decreased without changing the difference of potential atthe are itself or requiring any adjustment of the regulatingmagnet N.The amount of current flowing through the lamp I have found to be almostexactly that which would be produced under Ohms law by dividing thevoltage found by deducting the constant voltage of the are from theentire voltage by the number of ohms of the resistance IV at the time incircuit. In other words, if the magnet N is adjusted to maintain an arcof forty-five volts, and considering the voltage of the circuit 1 2 tobe one hundred and twenty volts, the difference between the two voltageswill be seventy-five volts and the current flowing through the arc willbe equal in amperes to seventy-five volts divided by the number of ohmsof the resistance IV which are in circuit.

In Fig. 9 I have given the resistance in ohms of the several sections ofthe resistance IV above that resistance in the figure, and below theresistance the number of amperes are marked at the severalcontact-points. Thus if the arm of the rheostat is thrown to the firstcontact at the left of the resistance there will be three ohms incircuit and the current will be twenty-five am peres. If moved one pointto the right, the resistance of IV in the circuit will be 3.4 ohms andthe current flowing through the arc will be twenty-two amperes, and soon. The effect of varying the current in the lamp is to vary the lengthof the are, a shorter are being produced for a smaller current; and thisis an exceedingly desirable feature of my lamp, since it enables thebrilliancy of the light to be varied for the production of dissolvingeffects for the stereopticon and for stage-lighting and like purposes bysimply adjusting the resistance IV.

hat I claim is 1. In an arc-lamp, the combination with thecarbon-holders, of a spring clock-train, having an initial tension andmounted in a frame having a fixed position, said clock-train act ing topositively feed the carbons together, a regulating-electromagnet forcontrolling the feeding movement, located in a constantlyclosedshunt-circuit around the are and blockin g the clock-movement in theretracted position of its armature, and an electromagnet located inseries with the arc and acting to separate the carbons to form the arcindependentl y of the feeding mechanism, whereby varying quantities ofcurrent may be passed through the lamp without affecting the regulationthereof, substantially as set forth.

2. In a focusing arc-lamp, the combination with the carbon-holders, of aspring clocktrain, having an initial tension and mounted in a framehaving a fixed position, said clocktrain being connect-ed with the twocarbonholders and acting to feed such carbon-holders positively togetherwith a proper relative rate of movement, a regulating-electromagnet forcontrolling the feeding movement, located in a constantly-closedshunt-circuit around the arc and blocking the clock-movement in theretracted position of its armature, and an electromagnet located inseries with the arc and acting to separate the carbons to form the areindependently of the feeding mechanism, whereby varying tpiantities ofcurrent may be passed through the lamp without affooting the regulationthereof, substantially as set forth.

3. In an arc-lam p, the combination with the two carbon-holders andoperating-racks, of pinions of different sizes engaging said racks andfixed to the same shaft, a driving-spring having an initial tensionconnected with said shaft, an escapement-train connected with said shaftthrough a pawl and ratchet so as to retard the shaft when driven by thespring and acting to feed the carbons together, and an electromagnetlocated in a shunt around the are, the armature of said magnet lockingthe escapement in its retracted position, whereby varying quantities ofcurrent may be passed through the lamp without aifectin g the regulationthereof, substantially as set forth.

In an arc-lamp, the combination with the two carbon-holders andoperating-racks, of pinions of different sizes engaging said racks andfixed to the same shaft, a driving-spring having an initial tensionconnected with said shaft, an. escapement-train connected with saidshaft through a pawl. and ratchet so as to retard the shaft when drivenby the spring and acting to feed the carbons together, aneleetron'lagnet located in a shunt around the are, the armature of saidmagnet locking the escapement in its retracted position, and a striking-magnet in series with the are, whereby varying quantities of currentmay be passed through the lamp without aifecting the regulation thereof,substantially as set forth.

5. In an arclamp, the combination with the positive-carbon holder havinga sliding movement, of the negative-carbon holder arranged in advance ofthe positive-carbol'i holder so as to produce the crater of the are onthe front side of the positive carbon, a pivoted support upon which thenegative-carbon holder is mounted, and a magnet in series with the aremoving said support on its pivot for striking the are, the point of thenegative carbon being thereby moved in an arc of a circle laterally awayfrom the positive carbon, substantially as set forth.

6. In an are-lamp, the combination of the positive and negative carbonholders, and a feeding mechanism feeding them together at a rateproportional to the l)llll'llll 3,' rate of the carbons, a slide carriedby the front of the lamp-case upon which the negativecarbon holder ismovably mounted, and a strikingmagnet also carried by said slide formoving the negative-carbon holder independent of the slide,substantially as set forth.

7. In a focusing arc-lamp, the conibimition with the positive andnegative carbons and the slottedlight-shield O, of the plate 1 projecting forward from the back plate of the light-shield above its lowerslots and partially encircling the negative carbon, substantially as setforth.

8. In an are-lamp, the combination with the movement-case A and thecarbon-holdcrs, of the light-shield O and front plate IQ for protectingthe movement from the heatoftl 3 are by means of the two air-spaceslocated respectively between the mmement-case and the plate K, andbetween said plate and the iigh tshield O, substantially as set forth.

9. In an arc-lamp, the eonlbination with the case A and thefeeding-motor and controllingmagnet inclosed thereby, of the racks ll,ll, passing through the top of the case, carbonholders J, L, connectedwith said racks, guiderod I, and guide-plate K, substantially as setforth.

10. In an arc-lamp, the combination with the case A inclosii'ig andsupporting the mechanism of the lamp, of the tubular clamp u, tube a,screw 0 and post (Z for supportingtho lamp and providing for itsvertical. adjustment, substantially as set forth.

11. In an arc-lamp, the combination, with the case A inclosing andsupporting the mechanism of the lamp and mounted upon averticallyadjust-able pivoted support, of the screw 0 and spring 0 foradjusting the lamp laterally, substantially as set forth.

In testimony that I. claimv the foregoing as my invention 1 have signedmy name, in presence of two witnesses, this 5th day of June, 18%.

E D WARD POWELL llOiKlX S.

\Vitnesses:

D. llICFAItLAX Moonu, PETER 1". Porn.

